Meet the animals that breathe through their skin, gut, and more

3 min readNew DelhiJul 18, 2026 11:00 AM IST

Several freshwater loaches, including the weather loach, have evolved an unusual survival strategy for oxygen-poor waters (Photo: Wikipedia)

When we think of breathing, lungs and gills usually come to mind. But in the animal kingdom, evolution has produced some truly bizarre ways of taking in oxygen. Some species absorb oxygen through their skin, others use specialised organs near their tails, while one marine creature even breathes through its rear. These remarkable adaptations help animals survive harsh environments, escape predators and endure long periods underwater.

Here are five animals with some of the most fascinating breathing mechanisms in nature.

1. Freshwater turtles: The famous “butt breathers”

Some freshwater turtles, including the Fitzroy River turtle and Murray River turtle of Australia, can absorb oxygen through their cloaca—a multi-purpose opening used for excretion and reproduction. During winter, when they hibernate underwater for weeks or even months, specialised sacs inside the cloaca extract dissolved oxygen from the surrounding water. This process, known as cloacal respiration, reduces the need to surface for air and helps the turtles survive in cold rivers where metabolism slows dramatically.

2. Sea cucumbers: Breathing through their rear end

Sea cucumbers have one of the strangest respiratory systems in the ocean. They draw seawater into their cloaca, where it passes through highly branched respiratory trees that extract oxygen before the water is expelled. Although this has earned them the nickname “butt breathers,” the adaptation is a highly efficient solution for animals that spend their lives on the ocean floor.

3. Lungless salamanders: They breathe through their skin

Members of the Plethodontidae family don’t have lungs at all. Instead, they absorb oxygen directly through their moist skin and the lining of their mouths. Because of this, they must remain in cool, damp environments where their skin stays wet enough for efficient gas exchange. They are among the most successful salamanders on Earth despite lacking lungs entirely.

4. Loaches: Fish that breathe using their intestines

Several freshwater loaches, including the weather loach, have evolved an unusual survival strategy for oxygen-poor waters. They gulp air at the surface, pass it into their intestine, where oxygen is absorbed into the bloodstream, and then expel the remaining gases. This adaptation allows them to survive in muddy ponds and stagnant waters where dissolved oxygen levels are extremely low.

5. Birds: Their lungs are powered by an extraordinary air-sac system

Birds don’t breathe like mammals. Instead of air moving in and out of the lungs in a simple cycle, they possess a network of air sacs that creates a continuous, one-way flow of fresh air through the lungs. This highly efficient system allows birds to extract more oxygen than mammals, helping them sustain long-distance migrations and fly at extremely high altitudes, including over the Himalayas.

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